Wireless communication networks are designed for convenient data exchange between devices. Communication between one device and another in the network occurs across a wireless link, where the transmitting device or transmitter emits certain electromagnetic signals from its antenna which propagate over the wireless link and are picked up by the antenna of the receiving device or receiver.
Recently, millimeter wave systems operating in the 60 GHz frequency band have been specified to provide data rates of several Gigabits per second (Gbps) over short range (typically up to 10 m). The very wide bandwidth available in the 60 GHz band (7 GHz in most major jurisdictions) means such wireless networks are capable of providing very high data throughput up to several Gigabits per second (Gbps) to support applications such as high-definition video streaming and high-speed bulk data download/upload between devices. Furthermore, one characteristic of 60 GHz wireless networks is that, due to the small RF wavelength (approximately 5 mm), high antenna gain is required to reach the required Signal to Noise Ratio (SNR) over the wide bandwidth with limited transmitter power (typical maximum 10 dBm). Therefore, devices in the network may employ directional antennas, and the antenna beams may be adaptively adjusted to maximize the link quality between each pair of devices. Directional antennas may in principle be used to allow spatial reuse—that is, the directionality of the antennas may reduce the mutual interference between multiple pairs of devices in the same network so that they may be co-scheduled in order to transmit simultaneously on the same channel (i.e. in the same frequency band and at the same time). In such networks, device scheduling (e.g. for further resource allocation to devices) is performed by a network coordinating device or network coordinator. The network coordinator is part of the network and may also be scheduled for communicating in a pair with another device either as a receiver or as a transmitter. When a device wants to join such a wireless telecommunication network, it sends a request to the network coordinator, which will further schedule the device for communicating. Furthermore, pairs of devices that are in an active link, i.e. that have already been scheduled or have made a request for scheduling and are waiting to be scheduled, generally perform a beam training procedure periodically in order to determine the best (highly directional) beam pattern to use on both sides.
In US patent application “Techniques for Wireless Personal Area Network Communications With Efficient Spatial Reuse” (Ser. No. 11/855,862), an interference matrix is generated by the network coordinator with elements comprising an estimate of the interference power that would be caused to one link in a pair of devices by another link in another pair of devices if they were to be co-scheduled. This interference matrix is generated by receivers listening, at different times (i.e. in turn), to the signal from transmitters of other links (i.e. in other pairs of devices). This signal power is then reported by the receivers to the network coordinator. Then, when a request of a device to be scheduled is made that cannot be fulfilled using pure TDMA (i.e. without spatial reuse), then the interference matrix is consulted to find links that can be co-scheduled (i.e. spatial reuse) with low mutual interference in order to make space to grant the new request. The disadvantages of this solution are that, since the beam training for each pair of devices is performed independently and using a finite set of beam patterns that are not optimized to minimize interference, the amount of spatial reuse that is possible will be considerably lower, and hence the aggregate data throughput of the network will not be optimized. In addition, due to the bursty nature of data traffic, the interference levels detected during data communications are not an optimal parameter for further deciding which pairs of devices may be co-scheduled as they may not represent the worst-case interference that will occur if the pairs are co-scheduled. Moreover, once some co-scheduling has been granted to a plurality of pairs of devices, the mutual interference between each individual link can no longer be determined by this solution and revocation of the co-scheduling is necessary, which may cause certain links to be dropped or have outages.
Today there is no solution to efficiently schedule devices that allows reducing interference and thus improving the efficiency of such wireless telecommunication systems. Today there is a need for an efficient device scheduling solution that can be easily implemented on the existing communication infrastructures.